When Worlds Collide

We know, original title. We'll come up with something new later.

Be warned: there may be some scenes that are a bit disturbing to some readers, meaning it can get bloody. Sorry...

What happens when the Vikings of Berk meet the soldiers from District 12? When the Greek demigods meet the old dragon rider from Alagaësia? When the four groups find the runner from the Glade? And when two of their enemies combine into one formidable force?

Chaos happens, that's what.